Chicago Municipal Code Section 8-20-100 says, in relevant part, that "no firearm may be sold, acquired or otherwise transferred wtihin the city, except through inheritance of the firearm." Firearms dealers and would-be gun buyers sued, arguing that it violated the Second Amendment. Judge Chang agreed, granting summary judgment in their favor.

The court used the two-step process sanctioned by the Seventh Circuit: first, the court determined whether the ban fell within the Second Amendment as it was understood in 1791 (when the Bill of Rights was ratified) or in 1868 (when the Fourteenth Amendment was ratified); second, the court determined whether the ban satisfies a varying, but heightened, level of scrutiny.

As to step one, the court concluded that "[t]he City's proffered historical evidence fails to establish that governments banned gun sales and transfers at the time of the Second Amendment's enactment," and therefore the Second Amendment applies. As to step two, the court applied "not quite strict scrutiny" (because the ban "prevents Chicagoans from fulfilling, within the limits of Chicago, the most fundamental prerequisite of legal gun ownership--that of simple acquisition") and that the ban didn't sufficiently serve the city's interests in reducing criminals' access to guns, restricting gun acquisition in the illegal market, or eliminating dangerous gun stores from Chicago.

Judge Chang gave the city "limited time, before the judgment becomes effective, to consider and enact other sales-and-transfer restrictions short of a complete ban," and invited the city to move for a stay pending appeal.